Sensor catheter having reduced cross-talk wiring arrangements

ABSTRACT

Improved wiring arrangements for sensor catheters are provided to reduce wire-to-wire cross-talk wherein wires connecting the sensor of the sensor catheter to a processing unit are divided into a plurality of wire bundles contained within respective sheaths, with the wires in wire bundle twisted together reduce electromagnetic signal interference among the individual wires, or between wire bundles.

REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/431,332 filed on Mar. 27, 2012, now U.S. Pat. No. 8,795,203, which isa continuation of U.S. patent application Ser. No. 10/668,451, filed onSep. 22, 2003, now U.S. Pat. No. 8,162,856, which claims the benefit ofU.S. provisional patent application Ser. No. 60/413,267, filed Sep. 23,2002, each of which is hereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

This application relates to medical devices such as catheters that havesensors at their distal tips to which electrical wiring is connected.

Sensor catheters are used to gather information during medicalprocedures for diagnosing and treating patients. Ultrasonic imagingcatheters, for example, may be used to gather ultrasonic images of apatient's blood vessels. Alternative imaging techniques also may beused, such as magnetic resonance imaging, optical coherence tomographyand infrared imaging. During certain procedures, catheters may be usedto gather a variety of physiological parameters such as temperature,pressure, pH, flow velocity and/or volumetric flow. Gradients or changesin physiological parameters across an area of interest may also bedetermined.

Sensor catheters are typically connected to control and analysisequipment, which may be used to generate images from raw imaging dataand display physiological parameters. A number of wires must be runalong the length of a typical catheter to connect the control andanalysis equipment disposed at the catheter's proximal end to thesensor(s) disposed at the distal catheter tip.

In many instances, there are seven or more wires that convey powersupply voltages, ground potential, drive signals, and raw sensor signalsto and from the catheter sensors. These wires may be organized as asingle cable bundle. However, cross-talk or noise among signal wires isa source of interference when using a sensor catheter to gather sensormeasurements. This may adversely affect ringdown performance.

In view of the above, it would be desirable to provide an imagingcatheter including improved wiring arrangements, to reduce wire-to-wirecross-talk.

SUMMARY OF THE INVENTION

In view of the foregoing, it is an object of the present invention toprovide a sensor catheter having improved wiring arrangements forreducing wire-to-wire cross-talk.

In accordance with the principles of the present invention, sensorcatheters are provided having improved wiring arrangements that reducewire-to-wire cross-talk. The wires are grouped in distinct subgroupssuch as pairs of wires or groups of three or more wires that carryrelated signals. Accordingly, a group of seven wires may be divided intotwo twisted wire pairs and one group of three twisted wires. In thismanner, wire-to-wire cross-talk is reduced.

By way of example, in an ultrasonic imaging catheter, the two wires thatcarry sensor signals from the ultrasonic imaging catheter may be groupedtogether and twisted closely together as a pair. As a result, cross-talkbetween the two wires is reduced, especially when compared to wirearrangements in which all of the wires are arranged in a single bundle.In addition, wires associated with ultrasonic drive signals also may begrouped together as a pair. Likewise, wires carrying power supply andclock signals (e.g., for use by multiplexer circuits at the catheter'sdistal end) may be grouped together as a pair.

The above examples are merely illustrative arrangements. According tothe present invention, sensor catheters having varying signaling needsand signal wires will require different wire subgroup arrangements. Theresulting wire subgroup arrangements may be twisted together to form asingle wire group formed of multiple wire subgroups.

Further features of the invention, its nature and various advantageswill be more apparent from the accompanying drawings and the followingdetailed description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and advantages of the present invention willbe apparent upon consideration of the following detailed description,taken in conjunction with the accompanying drawings, in which likereference characters refer to like parts throughout, and in which:

FIG. 1 is a side view of a previously known sensor catheter system;

FIG. 2 is a side-sectional view of the previously known sensor catheterof FIG. 1;

FIG. 3 is a cross-sectional view of a previously known wire bundle for asensor catheter;

FIG. 4 is cross-sectional view of a first embodiment of a wiringarrangement for a sensor catheter constructed in accordance with theprinciples of the present invention;

FIG. 5 is cross-sectional view of a second embodiment of a wiringarrangement for a sensor catheter constructed in accordance with theprinciples of the present invention; and

FIG. 6 is cross-sectional view of a third embodiment of a wiringarrangement for a sensor catheter of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, a previously known sensor catheter system 10comprises catheter 12 including proximal end 12 a attached to processingequipment 14 and distal end 12 b including sensor assembly 16 comprisingone or more sensors. By way of example, sensor assembly 16 may includesa temperature sensor, a pressure sensor, a pH sensor, a flow velocitysensor and/or a volumetric flow sensor for measuring temperature,pressure, pH, flow velocity and flow volume. Of course, sensor assembly16 may include sensors other than those listed above.

Sensor assembly 16 also may include an imaging sensor, such as anultrasound, magnetic resonance, optical coherence tomography or infraredimaging sensor. Imaging sensors are typically used to gather images fromlocations inside a patient's body during surgical and diagnosticprocedures. Catheter 12 may be configured to gather images from inside apatient's blood vessels during percutaneous procedures such ascardiological or peripheral intervention. An illustrative catheter thatmay be used for ultrasound applications is described in commonlyassigned U.S. patent application Ser. No. 10/233,870, filed Aug. 29,2002.

Referring to FIG. 2, signals from sensor 16 are transmitted to and fromprocessing equipment 14 via wire bundle 18 including a plurality ofwires. Sensor assembly 16 may include an ultrasound sensor thattransmits signals to processing equipment 14, which processes the signaldata and displays the resulting images on a suitable display screen.Alternatively, sensor assembly 16 may include other sensors thattransmit different signals to the processing equipment.

Processing equipment 14 also transmits signals that control theoperation of sensor assembly 16. For example, if catheter 12 is anultrasound imaging catheter, processing equipment 14 transmits drivesignals for one or more transducer elements disposed within the sensorassembly. These drive signals cause the transducer elements to emitacoustic vibrations directed towards a target area within the patient'sbody.

Power supply signals and clock signals (e.g., for synchronizing thetiming of circuitry within sensor assembly 16) also may be transmittedto sensor assembly 16 from processing equipment 14 via wire bundle 18.In order to improve overall system performance, it is desirable toreduce cross-talk between the different wires, regardless of the type ofsignal being transmitted.

Referring now to FIG. 3, a previously known wiring arrangement 20 for asensor catheter comprises a single wire bundle having six individualwires 20 a radially surrounding central wire 20 b. Wiring arrangementfurther comprises outer sheath 21 for retaining the wires 20 a and 20 b.This arrangement has the advantage of being relatively compact, butsuffers from a relatively high degree of wire-to-wire cross-talk.

Referring to FIG. 4, a first embodiment of a wiring arrangement forsensor catheter 12 constructed in accordance with the principles of thepresent invention is described. Wiring arrangement 22 comprises firstwire bundle 24 contained within sheath 25, second wire bundle 26contained within sheath 27 and tird wire bundle 28 contained withinsheath 29. First wire bundle 24 includes wires 24 a and 24 b, which aretwisted together to assist in electrically isolating the wires from theenvironment, thereby reducing electromagnetic signal interference amongthe individual wires. Similarly, second wire bundle 26 includes wires 26a and 26 b that are twisted together; third wire bundle 28 includeswires 28 a, 28 b and 28 c that are twisted together. All three wirebundles 24, 26 and 28 are twisted together to form wiring arrangement 22and housed within outer sheath 30.

Referring to FIG. 5, a second embodiment of a wiring arrangement forsensor catheter 12 constructed in accordance with the principles of thepresent invention is described. Wiring arrangement 32 comprises firstwire bundle 34 contained within sheath 35, second wire bundle 36contained within sheath 37 and third wire bundle 38 contained withinsheath 39. First wire bundle 34 includes wires 34 a and 34 b, which aretwisted together to assist in electrically isolating the wires from theenvironment, thereby reducing electromagnetic signal interference amongthe individual wires. Similarly, second wire bundle 36 includes wires 36a and 36 b that are twisted together; third wire bundle 38 includeswires 38 a, 38 b and 38 c that are twisted together. Unlike theembodiment of FIG. 4, wire bundles 34, 36 and 38 of the embodiment ofFIG. 5 are not twisted and retained within an outer sheath.

Referring to FIG. 6, a third embodiment of a wiring arrangement forsensor catheter 12 of the present invention is described. Wiringarrangement 42 comprises first wire bundle 44 contained within sheath45, second wire bundle 46 contained within sheath 47 and third wirebundle 48 contained within sheath 49. The first pair of wires includeswires 44 a, 44 b and 44 c, which are twisted together to assist inelectrically isolating the wires from the environment, thereby reducingelectromagnetic signal interference among the individual wires.Similarly, second wire bundle 46 includes wires 46 a, 46 b and 46 c thatare twisted together; third wire bundle 48 includes wires 48 a, 48 b and48 c that are twisted together. All three wire bundles 44, 46 and 48 aretwisted together to form wiring arrangement 42 and contained within anouter sheath 50.

Twisting the wires in the wire bundles has been observed to reduceelectromagnetic interference among the wires. In some embodiments, thewires are twisted in a clockwise direction, while in others the wiresmay be twisted in a counter-clockwise direction. Alternatively, wireswithin different bundles may be twisted in different directionsdepending upon the application of the sensor catheter. Moreover,multiple wire bundles may be twisted together to form a single wiregroup. When forming a single wire group from multiple wire bundles, thedirection of wire bundle twisting preferably is opposite to thedirection in which individual wires are twisted when forming themultiple wire bundles.

The wiring arrangements of FIGS. 4-6 are merely illustrative. As wouldbe appreciated by those of skill in the art, many different wiringarrangements are possible without departing from the scope of thepresent invention. For example, the wiring arrangement may include 2 ormore wire bundles, each wire bundle including two or more individualwires.

Although preferred illustrative embodiments of the present invention aredescribed above, it will be evident to one skilled in the art thatvarious changes and modifications may be made without departing from theinvention. It is intended in the appended claims to cover all suchchanges and modifications that fall within the true spirit and scope ofthe invention.

The invention claimed is:
 1. A medical device for ultrasound imaging,the medical device comprising: an elongate body comprising proximal anddistal portions; an ultrasound transducer disposed at the distal portionof the elongate body, the ultrasound transducer comprising a pluralityof transducer elements; and a plurality of wires in communication withthe ultrasound transducer, related to operation of the ultrasoundtransducer, and disposed in a configuration to reduce electromagneticinterference, the configuration including: the plurality of wiresdivided into at least first and second wire bundles; the first wirebundle configured to direct drive operations of one or more transducerelements and comprising at least two wires twisted together; the secondwire bundle configured to direct a power supply to the ultrasoundtransducer and comprising at least two wires twisted together; and thefirst and second wire bundles being helically twisted around one anotherwith the wires of the first bundle not being in direct contact with thewires of the second bundle.
 2. The medical device of claim 1, whereinthe first wire bundle is disposed within a first sheath.
 3. The medicaldevice of claim 2, wherein the second wire bundle is disposed within asecond sheath.
 4. The medical device of claim 1, wherein the wires ofthe first wire bundle, the second wire bundle, or both are twisted in afirst direction.
 5. The medical device of claim 4, wherein the first andsecond wire bundles are twisted together in a second direction differentfrom the first direction.
 6. The medical device of claim 1, wherein thefirst and second wire bundles are disposed within a third sheath.
 7. Themedical device of claim 1, wherein the plurality of wires are furtherdivided into at least a third wire bundle.
 8. The medical device ofclaim 7, wherein the third wire bundle is configured to carry receivedultrasound signals from the ultrasound transducer and comprises at leasttwo wires twisted together.
 9. The medical device of claim 1, whereinthe second wire bundle is further configured to direct clock signals tothe ultrasound transducer.
 10. The medical device of claim 1, wherein atleast one of the plurality of wires is configured to provide a ground.11. A medical device for ultrasound imaging, the medical devicecomprising: an elongate body comprising proximal and distal portions; anultrasound transducer disposed at the distal portion of the elongatebody, the ultrasound transducer comprising a plurality of transducerelements; and a plurality of wires in communication with the ultrasoundtransducer, related to operation of the ultrasound transducer, anddisposed in a configuration to reduce electromagnetic interference, theconfiguration including: the plurality of wires divided into at leastfirst and second wire bundles; the first wire bundle configured todirect drive operations of one or more transducer elements andcomprising at least two wires twisted together; the second wire bundleconfigured to carry received ultrasound signals from the ultrasoundtransducer and comprising at least two wires twisted together; and thefirst and second wire bundles being helically twisted around one anotherwith the wires of the first wire bundle not being in direct contact withthe wires of the second wire bundle.
 12. The medical device of claim 11,wherein the first wire bundle is disposed within a first sheath.
 13. Themedical device of claim 12, wherein the second wire bundle is disposedwithin a second sheath.
 14. The medical device of claim 11, wherein thewires of the first wire bundle, the second wire bundle, or both aretwisted in a first direction.
 15. The medical device of claim 14,wherein the first and second wire bundles are twisted together in asecond direction different from the first direction.
 16. The medicaldevice of claim 14, wherein the first and second wire bundles aredisposed within a third sheath.
 17. The medical device of claim 11,wherein the plurality of wires is further divided into at least a thirdwire bundle.
 18. The medical device of claim 17, wherein the third wirebundle configured to direct clock signals to the ultrasound transducerand comprises at least two wires twisted together.
 19. The medicaldevice of claim 11, wherein at least one wire of the plurality of wiresis configured to provide a ground.